[UCI-Calit2] REMINDER: Networked Systems Distinguished Speaker Series

[Anna Lynn Spitzer]

REMINDER


DATE: Thursday, May 18, 2006
TIME: 2-3p.m., refreshments at 1:45
PLACE: Calit2 3008

Avoiding Oscillations due to Intelligent Route Control Systems

SPEAKER:
Constantine Dovrolis
Georgia Tech


Abstract

Intelligent Route Control (IRC) systems are increasingly deployed in
multihomed networks. IRC systems aim to optimize the cost and
performance of outgoing traffic, based on measurement-driven dynamic
path-switching techniques. In this paper, we first show that IRC systems
can introduce sustained traffic oscillations, causing
significant performance degradation instead of improvement. This
happens, first, when IRC systems do not take into account the self-load
effect, i.e., when they ignore that the performance of a path can change
after additional traffic is switched to that path. Second, oscillations
can take place when different IRC systems get synchronized due to
significant overlap of their measurement time windows. We then propose
measurement methodologies and path-switching algorithms that can
effectively deal with the previous two issues. The proposed IRC
techniques use available bandwidth estimation to avoid the self-load
effect, and they introduce a random component in the path-switching
decision or time scale. We evaluate the proposed techniques under
diverse traffic conditions. When the background traffic is stationary,
IRC systems should switch paths conservatively, only upon major traffic
fluctuations. With nonstationary background traffic and congestion
periods that last for a time scale Tw, IRC systems improve performance
only if they can detect congestion and switch paths much faster than Tw;
otherwise, they cause oscillations and hurt performance. We also show
that the gradual deployment of randomized IRC systems, in the presence
of traffic from deterministic IRC systems, can play a stabilizing role
and benefits early adopters.

Bio:

Constantine Dovrolis is an assistant professor at the College of
Computing of the Georgia Institute of Technology. He received the
Computer Engineering degree from the Technical University of Crete
(Greece) in 1995, the M.S. degree from the University of Rochester in
1996, and the Ph.D. degree from the University of Wisconsin-Madison in
2000.  His research interests include methodologies and applications of
network measurements, bandwidth estimation algorithms and tools, overlay
networks, service differentiation, and network problem diagnosis.  He
received the NSF CAREER award in 2004.

For further information, please contact Athina Markopoulou at
athina at uci.edu.